Solid-state lighting devices may be operated at various lighting intensity levels to provide various levels of illumination. In some cases, lighting device output has an effect on curing time of a device being manufactured or other process variable. Therefore, it may be desirable to provide a consistent known level of light intensity to reduce product variation. However, power is often supplied to a lighting array via a voltage regulator. The initial output of the voltage regulator may be inconsistent between different levels of illumination from the lighting array. For example, if 40% of available voltage regular output is requested for a desired level of light intensity, it may take the voltage regulator 15 ms to output voltage sufficient to provide the desired level of light intensity. However, if 100% of available voltage regulator output is requested for a desired level of light intensity, it may take the voltage regulator 2 ms to output voltage sufficient to provide the desired level of light intensity. The response time lag may be attributed to charging of resistor/capacitor networks within the voltage regulator. It may be desirable for output of the voltage regulator to respond in a way that provides more consistent starting times between the various levels of requested lighting intensity so that output from the lighting array may be more consistent.
The inventor herein has recognized the above-mentioned disadvantages and has developed a system for operating one or more light emitting devices, comprising: an array of solid state lighting devices; a voltage regulator including a voltage regulator input, the voltage regulator electrically coupled to the array of solid state lighting devices; and an analog pre-charge circuit having a pre-charge circuit output, the pre-charge circuit output electrically coupled to the voltage regulator input, the analog pre-charge circuit including an pre-charge circuit input, the pre-charge circuit input electrically coupled to the array of solid state lighting devices, the analog pre-charge circuit including a timing circuit, the analog pre-charge circuit including a first capacitor and a first resistor electrically coupled to the timing circuit.
By controlling providing an input to a voltage regulator from an analog pre-charge circuit, it may be possible to more precisely control light intensity of a lighting array during lighting array power-up conditions. The analog pre-charge circuit may output a voltage pulse having a duration that is controlled as a function of time or a voltage that develops at solid state lighting devices. The analog pre-charge circuit may output a voltage of a predetermined duration when a lower level of light intensity is requested. The voltage pulse of the predetermined duration acts to rapidly charge resistor/capacitor networks within the voltage regulator so that the required light intensity may be provided. The analog pre-charge circuit may output a voltage pulse with a duration that is limited by a voltage that develops at the solid state lighting devices for higher levels of requested light intensity. By limiting the analog pre-charge circuit output voltage in response to a voltage at the lighting devices, voltage regulator output may be controlled to conserve energy and reduce the possibility of exceeding the desired light intensity level.
The present description may provide several advantages. In particular, the approach may improve lighting system light intensity control. Further, the approach may provide improve power consumption. Further still, the approach may be provided without need of a sophisticated digital controller.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.